$-5kl + 2l + 8m + 5 = 10l + 9m + 4$ Solve for $k$.
Explanation: Combine constant terms on the right. $-5kl + 2l + 8m + {5} = 10l + 9m + {4}$ $-5kl + 2l + 8m = 10l + 9m - {1}$ Combine $m$ terms on the right. $-5kl + 2l + {8m} = 10l + {9m} - 1$ $-5kl + 2l = 10l + {m} - 1$ Combine $l$ terms on the right. $-5kl + {2l} = {10l} + m - 1$ $-5kl = {8l} + m - 1$ Isolate $k$ $-{5}k{l} = 8l + m - 1$ $k = \dfrac{ 8l + m - 1 }{ -{5l} }$ Swap the signs so the denominator isn't negative. $k = \dfrac{ -{8}l - {1}m + {1} }{ {5l} }$